Llyn Tegid Safety Works

What’s the work being planned for Llyn Tegid? The embankments are being investigated for their ability to withstand extreme flood events. This includes an assessment of their height, composition and erosion protection measures such as the stone wave protection on the upstream face. The embankments included in the assessment run along the lake shore from the Bala Adventure and Watersports Centre, around the Enterprise Park bordering the River Dee and Tryweryn, up as far as the A494 bridge.

Why is the work necessary? The work is necessary to ensure that Llyn Tegid continues to meet the requirements of the Reservoirs Act 1975 and remains safe in the long term. Llyn Tegid is regulated under the Act which requires regular inspections by qualified reservoir Inspecting Engineers. At the last inspection in 2014 some statutory recommendations were made to which this scheme relates.

When will it start? Construction work is extremely unlikely to start before Spring/ Summer 2019 depending on planning and other approvals that may be necessary.

When will the work be completed? The project is at a very early stage and it is not possible to be definitive about timescales before a solution has been agreed. At this stage it is estimated that the construction may not be completed until 2021.

How much disruption can we expect? It is likely that sections of footpaths may have to be closed and diverted for limited periods. There will also be increased construction traffic related to the works. However, the construction phase of the project will be carefully managed to minimise the amount of disruption to the local community. Where possible, work will be phased and affected stakeholders will be consulted on the approach adopted.

How are you considering the exceptional environmental quality of the lake and its surroundings? Llyn Tegid is situated in the Snowdonia National Park and the embankments are within environmentally sensitive areas of international importance. Sympathetic solutions will be explored and opportunities identified to enhance the environment in line with the requirements under the Environment (Wales) Act 2016 and Well-being of Future Generations (Wales) Act 2015. We will be consulting closely with Snowdonia National Park Authority, our own natural resources team responsible for the protected sites affected, and other key stakeholders to ensure that all possible solutions are appropriately assessed, impacts minimised and enhancement opportunities identified.

What about the impact on people’s recreational use of the lake and shore? Recreational use of the lake itself is very unlikely to be affected by the scheme. However, there may be some disruption to sections of footpaths during the project, which will be minimised as far as possible.

**What about the impact on tourism?** The construction works will be managed sensitively to minimise any potential impacts on tourism. We will consult fully with the local community and other key stakeholders as the solution is developed to make sure that it is delivered in an acceptable way.

In the long term, we hope the scheme will have a positive impact on tourism and the local economy. Maintaining the access along the lake shore and its magnificent views are a key consideration during the appraisal process.

**What will be the first thing we’ll see?** Over the coming months, you may see increased investigation activity in the area. This is to help provide technical background information on which options can be evaluated and developed. This is likely to include ground investigation works, topographical and environmental surveys. Whilst this will be highly visible, they are all relatively short duration activities. We will have to make some minor footpath diversions to ensure public safety, however this should not adversely affect your enjoyment of the local environment.

**When can we have our say and learn more?** We are engaging with key stakeholders throughout the appraisal process and will be keeping our website page up to date. Once we have identified the extent of the work required, we will hold drop-in sessions for people to learn more about the work and to take on board your views and requirements as we design the work in more detail.

**Who is doing the work?** We have appointed engineering consultancy firm Black & Veatch to undertake the initial appraisal phase of work. Subsequent detailed design work will be competitively tendered at the appropriate time.

**Who will consent the project?** Snowdonia National Park Authority will be responsible for determining planning permission for the project. There are also other permissions that will need to be obtained from Natural Resources Wales. Whilst part of the same organisation, technical and permitting staff operate independently and impartially with respect to their assessments.

**Will trees be removed?** It is possible that some trees may have to be removed depending on the extent of works required at different locations. This will only be done if necessary and environmental mitigation and enhancement opportunities will be identified to offset any potential impact.

All trees that could be affected will be fully assessed in an arboricultural survey and other habitat surveys as necessary so that their removal is appropriately managed.

**Does this affect the planned Railway project?** We are aware of the proposed extension to the Bala Lake Railway and are working closely with them to understand the requirements of their scheme and how the interactions with this project could be managed.

**Will the project affect the risk of flooding in Bala?** We are managing the risk of flooding to Bala in the long term and improving the safety of the embankments. This project will not increase the risk of flooding in the town and is likely to reduce the overall flood risk in the more extreme events.

**Will the capacity of the lake be increased?** The capacity of the lake will not be increased. Will the embankments be raised? It may be necessary to provide additional resilience in targeted locations, but there are significant sections of the embankment that are likely to remain at their current level. If defence levels do need to be increased in specific areas, this could be done in a number of ways including the construction of wave walls. Embankment raising is a possibility and is being assessed alongside other options at this stage.

How does water regulation work at Llyn Tegid? Llyn Tegid, Wales’ largest natural lake, first became a reservoir in the 19th Century. To guarantee a supply of water to the Shropshire Union Canal, Thomas Telford built sluices at the outlet of Llyn Tegid. Water released through these sluices was abstracted into the canal at Horseshoe Falls, Llangollen. Then, in the 1950’s, the Dee and Clwyd River Board built the Bala Lake Scheme. The lake’s natural outlet was lowered (bypassing Telford’s original sluices), and new sluice gates were built downstream of the confluence with the Afon Tryweryn. Embankments were built to contain water stored behind the sluice gates and to provide flood protection to the town of Bala. This provided around 21,000,000 m³ (cubic metres) of controllable, stored water in Llyn Tegid. This storage capability means that Llyn Tegid is considered a reservoir under the Reservoirs Act 1975. Today this reservoir is operated, alongside Llyn Celyn and Llyn Brenig, to ensure a continuous supply of water for abstraction from the River Dee. This can reach up to around 830 Ml/d (Megalitres per day), by three water companies and the Canal and Rivers Trust. In addition, flood water run-off is detained in Llyn Tegid, in a short-term and controlled way, to greatly reduce the frequency and extent of flooding in the Dee Valley downstream of Bala.

March 2018